Rough running 360

[Akauto]

Hey everyone

New guy to the forum here. I have a situation with my 2000 2500 5.9 gas. I got the truck about 4 months ago with what was thought to be a blown trans (turned out it wasnt) also it had misfire codes for cylinders 3 and 8 i believe. After further inspection i sae that the distributor ears for the cal were broken off. So i replaced the dist. cap, rotor, wires and plugs. I should say here that the #8 spark plug was so seized i took it out with a 1/2 inch breaker bar. I replaced the plenum gasket. Immediately upon starting the truck it ran rough at idle. Driving was ok but seemed to lack power and takes a while to fire up when hitting the key. 2 weeks ago it shot a check engine light the code is a P0305. I should also say that i went through all the sensors (map, IAC, throttle position...i replaced all but the map since it reads good on a scanner.

Can anyone help point me in the right direction? Maybe someone has had the same issues? Also the truck needs exhaust work...all of it, the y pipe is bad at the flanges and the muffler is shot.

Any info would be greatly appreciated!

 

[tommyboi87]

Clogged cat maybe? Mine was having a bad idle and had an occasional stall and didn't have much power. Turned out the cam sensor was shot.

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[dodge dude94]

Compression test time.

Cylinder 3 is rarely an issue. Unless an injector is out

 

[Kotta390]

I'm not sure about cylinder 3, that could be a separate issue, but on these trucks they have issues with cylinders 7&8 due to being hotter than the other cylinders and also get the most oil due to a leaking plenum gasket...

Which brings me to my next point, you need to look down your throttle body, with a flashlight check to see if there is oil there and any of it being pooled up inside. These magnum motors are notorious for blowing plenum gaskets because of the dissimilar metal exposure and different rates of thermal expansion. If it has oil replace the gasket immediately.

The gasket can cause lots of problems, some of them being ie; low power, detonation, carbon fouling/oil fouling on plugs, pinging and poor fuel mileage. I've been around these motors for 15 years now and they have little issues, this one being offered of the biggest and most overlooked.

 

[BlackMagnum2000]

Another issue often over looked is make sure the plug wires do not cross, or if they do make sure they do at a 90° angle. Try using the stock wire separators on the valve cover studs, or buy a set for about $5. It can cause many problems.


There can be many things that cause this. Has the distributor ever been out of the motor? Or turned? This can cause the fuel sync to be out of adjustment, causing injector timing to be off and causing misfires. That was what caused mine. However my misfire code kept jumping cylinders, it wasn't consistently any specific cylinders. I agree with the others, especially doing a compression test.

 

[Kotta390]

Fuel sync could be an issue like you said and the misfires can happen at multiple cylinders but I doubt he has the problem.


By all means go ahead and do a compression test and see what happens.

The plug wires crossing shouldn't be an issue unless the conduit is bad and is jumping spark.

 

[BlackMagnum2000]

The plug wires crossed could cause many problems on these engines. Even Dodge recognized this
http://dodgeram.info/tsb/1998/18-48-98/18-48-98-v8.htm